1. Field of the Invention
The present invention relates to handling or stock containers such as pallet transport or heightening boxes, also referred to as tote boxes.
2. Description of the Prior Art
Most containers or receptacles of this character comprise on one or several lateral walls an opening closed by one or more hinged shutters in order to facilitate the access to the packaged, bagged or like material or goods contained therein when the top portion of the material has already been removed. As a rule, these shutters are kept in their closed position by lock bolts or retaining hooks. However, both locking systems are attended by various inconveniences.
In fact, lock-bolt systems are relatively expensive and their operation requires the use of both hands. Besides, when closing the shutter it is necessary to position the shutter very accurately in the proper position to permit the engagement of the lock bolts into the corresponding retaining keepers.
Hook-type closing devices are advantageous in that they are very simple, since they consist only of a pair of hooks mounted along the edges of the opening and adapted to be engaged by fastening straps or loops carried by the matching sides of the corresponding shutter. In this case, the lower edge of the shutter is hingedly mounted by means of elongated rings affording a certain degree of liberty of movement in the vertical direction to facilitate the engagement of said straps or loops on the retaining hooks. The thus hooked shutter is subsequently kept in position by gravity.
However, the efficiency of this system is also objectionable for in case of shocks, jolts or vibration the straps or loops keeping the shutter in its closed position are likely to free themselves untimely from the corresponding retaining hooks. On the other hand, the shutters are not perfectly held against movement since considerably play is present at various points and for the same reason it is a frequent occurrence that operators do not properly fasten the shutters by using only one of the closing hooks.